1. Field of the Invention
This invention relates to a switcing circuit, and more particularly to a switching circuit using a semiconductor device for fade-in and/or fade-out operations.
2. Description of the Prior Art
Generally, a fade-in or fade-out operation is utilized as a special effect in a radio or a television. The fade-in or fade-out operation can be performed in such a manner that a signal gain is manually and gradually varied or that a circuit is used by which the signal gain is automatically varied for a given time. However, the manual control is inconvenient for consumers. And in the automatic control, the arrangement of the circuit is complicated and a fade-in time or a fade-out time cannot be varied. Accordingly, also the automatic control is inconvenient and not practical.